Experimental Study On Effect Of Total Glucosides Of Paeony On The Expression Of Interleukin-1 And Tumor Necrosis Factor-α In The Kidney Of Diabetic Rats

Background and objective Diabetic nephropathy(DN) has become one of the main cause of end-stage renal disease(ESRD),but unfortunately the intimate mechanisms leading to the development and progression of renal injury were not yet fully known. Accumulating evidence now indicates that Chronic low-grade infammation and activation of the innate immune system are closely involved in the pathogenesis of diabetes nephropathy.The proinflammatory cytokines,mainly tumor necrosis factor-a (TNF-a) and intefleukin-1(IL-1) play a significant role in its development and progression.The study in vivo and in vitro evidence demonstrated that anti-inflammatory treatment have significant protective effects on DN.Total glucosides of paeony(TGP) are active compounds extracted from the roots of the tradition herb Paeonia lactiflora Pall.It possesses a variety of pharmacological functions,include anti-inflammation,anti-oxidative stress and immunoregulatory activity.The purpose of the present study was to investigate the effect of TGP on the expression of interleukin-1 and tumor necrosis factor-αprotein and its the possible renoprotective effects mechanism in the kidney in experimental diabetic rat.Methods Fifty adult male Sprague-Dawley rats were separated into five groups at random.Control group(n=10),model group(n=10),model group treated with TGP (50 mg·kg^-1,by gavage,n=10),model group treated with TGP(100 mg·kg^-1,n=10) and model group treated with TGP(200 mg·kg^-1,n=10).To induce the experimental model of diabetes,rats received a single intraperitoneal injection of STZ(60mg·kg^-1·d^-1).TGP was orally administered.Control group and model group treated with the same vehicle alone.Eight weeks after STZ injection,the following determinations were done in samples:(1) plasma glucose(BG),liver function,kidney function and plasma lipid were determined according to standard methods;(2) 24 hours urinary albumin excretion rate(UAER) were measured by enzyme immunoassay(EIA);(3) Renal lesions were evaluated using PAS staining,the mean glomerular volume(V_G) and indices for tubulointerstitial injury(TII) were measured by using pathology image analysis system software;(4) Western-blotting for renal IL-1 and TNF-αprotein were quantified densitometrically;(5) Immunohistochemistry for transforming growth factor-β1 (TGF-β1) was performed by streptavidin-biotin complex(SABC) technique.Results 1.BG,Body weight(BW) ratio of KW to BW(KW/BW),UAER,liver function:8 weeks after STZ injection,there was a significant increase in BG(P＜0.01) and BW was significantly decreased(p＜0.01) in diabetic rats compared with control group.The BG level of TGP group(50 mg,100 mg and 200mg·kg^-1) haven no statistically significant difference compared with model group.KW/BW in TGP group (50 mg,100 mg and 200mg·kg^-1) was decreased compared with model group,but there have no statistically significant.UAER in model group were significantly higher than control group,and UAER in TGP group(50 mg,100 mg and 200mg.kg^-1) were significantly lower than model group(P＜0.05,P＜0.01).TC,TG and Creatinine clearance rate(Ccr) in model group was increased compared with control group,but TC,TG and Ccr in TGP group(50,100,200 mg·kg^-1) have no statistically significant difference compared with control group.In addition,ALT and AST have no difference between control group,model group,and TGP group(50,100,200 mg.kg^-1).It shows that TGP have no effect on liver function.2.Renal pathologic morphology:Compared with control group,V_G and TII in model group was significantly increased.V_G in TGP group(50 mg.kg^-1) was significantly lower than model group(P＜0.05),Tll in TGP group(50 mg.kg^-1) was lower than model group,but there have no statistically significant.V_G and TII in TGP group(100,200 mg.kg^-1) was significantly lower than model group(P＜0.05,P＜0.01 ).3.IL-1 and TNF-αprotein expression in renal tissue Western blot analysis noted that the expression of IL-1 and TNF-αprotein in the kidney were significantly increased in diabetic rats,which were all significantly inhibited by TGP treatment with 50,100 and 200 mg.kg^-1 in a dose-dependent manner.4.TGF-β1 expression in renal tissue There was minimal immunohistohemistry staining for TGF-β1 in glomeruli and tubulointerstitium of control group rats.Immunostaining for TGF-β1 was markedly increased in model group in glomeruli and tubulointerstitium., TGF-β1 expression in TGP group(50 mg.kg^-1) was lower than model group,but it didn't have statistically significant.TGF-β1 expression in TGP group(50,100,200 mg.kg^-1) were significant decreased compared with model group.Conclusion Our study suggest that TGP treatment ameliorates early renal injury via the inhibition of the overexpression of IL-1 and TNF-αprotein in the kidney in diabetic rats.